In this research, using asphalt decomposition test based on AASHTO-T164 standard, it is investigated how burnt oil and asphalt chips affect the properties of hot asphalt. In this study, burnt oil with different percentages was added to the worn bitumen which was extracted from the worn asphalt by extraction method and was subjected to penetration degree and softening point tests. The addition of rejuvenator increases the Marshall resistance's cause is to provide the necessary adhesion and cohesion between the aggregate and bitumen, but with the addition of a percentage of rejuvenator and increasing the penetration of bitumen, the adhesion and cohesion of bitumen and aggregates is reduced. This will reduce the durability of the samples, which is reduced with 20% of burnt bitumen oil and used in the asphalt mixture resulting from the mixing of asphalt chips and new materials. It is recommended to use 50% of asphalt chips to improve the physical properties of the mixture. The results show the effect of burnt oil as a rejuvenator for worn bitumen and with increasing the percentage of rejuvenating material, the parameters of worn bitumen also improve and also with increasing percentage of asphalt chips (RAP) in samples without Addition of new bitumen has been made, strength and durability have also increased and consequently the Marshall ratio has also increased.

One of the methods to improve the properties of asphalt mixtures is using additives. One of the additives that have received much attention in recent years is nanomaterials, which have been very popular due to their unique characteristics. In this study, the effects of nanographene on the performance characteristics of hot asphalt mixtures have been investigated. For this purpose, bitumen was modified in 0.1%, 0.3%, and 0.5% (by weight of bitumen), and by performing bitumen tests, the amount of nanographene selected was 0.5%. Then, to evaluate the performance characteristics of the mixtures, repeated axial load tests (RLA), indirect tensile strength modulus (ITSM), and indirect tensile fatigue test (ITF) were performed. Besides, to evaluate the moisture sensitivity of the mixtures, indirect and compressive tensile tests were performed on the samples in both dry and wet conditions. The results showed a decrease in the final deformation an increase in stiffness at 5, 25, and 40 by 15, 36, and 54%, respectively. Also, in some samples, the fatigue life of modified asphalt mixtures was improved by up to 55% compared to conventional mixtures. Increasing the TSR index in the indirect tensile test indicates an improvement in the performance of the modified sample compared to conventional samples and a decrease in their sensitivity against moisture, to the extent that the indirect tensile strength of the modified sample in dry and wet conditions compared to conventional samples Increased by 23% and 38% respectively.

In this paper, stripping phenomenon in hot mix asphalt in Iran has been studied. For this purpose the effect of lime and three types of liquid anti stripping agents on two types of stone materials, sensitive against stripping phenomenon, has been investigated. The liquid antistripping agent in this research has been selected from one of the most credited producers in this field and the dampness sensitivity of materials has been measured through AASHTO T 283. The economic evaluation has been done according to cost-benefit method for application of antistripping agents. The results show that using lime and anti-stripping agents, it would be possible to modify two types of materials which are sensitive against stripping. But it is required to study each material separately for evaluation of the effect of anti-stripping agents. The economic analysis is descriptive of the fact that in some projects, the application of anti-stripping agents results reduced costs, in addition to technical upgrading of materials quality.

Moisture damage or stripping is one the fundamental defects of asphaltic surface layers. Moisture damage has great effect on other defect types of asphalt surface layers. Generally, Moisture damage is loss of adhesion between asphalt binder and aggregates or loss of cohesion in asphaltbinder structure. Since hot mix asphalt is made of different components, performance improvement of each component will result better resistance against moisture damage effects. However, weight of asphalt binder as one of the components of hot asphalt concrete is not high, but hasmajor effect on the better performance, durability and stability of asphalt concrete mixtures and any change in asphalt binder performance has remarkable effects on the asphalt concrete performance. Nowadays, modifiers are used for modifying asphalt binders and upgrading its performance. Nanoparticles include Nano-clay are one of the modifier types that are used for modifying asphalt binders. Because of layered structure, Nano-clay would enhance performance properties of Nano composites. In this research, two types of Nano-clay is used for evaluating their effects on the Moisture damage resistance of asphalt concretes (montmorillonite CA and CB). Marshall Test, boiling texas test and image processing are used for un-compacted samples as well as moisture damage test (AASHTO T283) and resilient modulus test are used for compacted samples containing 0, 2, 4 and 6 percent of each Nano-clay modifier. Results show that asphalt concrete has better resistance to moisture damage by adding Nano-clay modifiers.

Fatigue cracks are considered as the main failures in bituminous layers of pavement. Hence, knowledge about the fatigue characteristics of these layers is important in design and evaluation of pavement. There is not enough information regarding to the fatigue properties of modified mixes with waste plastic bottles (PET). Indirect tensile stiffness and fatigue tests were performed at 5 and 20oC. Different amounts of PET (2 to 10% by weight of bitumen) were added to asphalt mixture in dry method. In this research in order to develope fatigue models for PET modified mixes. Based on obtained results the slope of correlated fatigue curves reduced upon reducing the testing temperature. At 210 microstrain level and above, the increasing in resilient modulus caused a reduction in fatigue life, whereas below 210 microstrain the reverse was true. Finally based on laborator y testing results distinct models were established for different boundary strain levels.

The pavement quality has a great impact on safety of road and convenience of driving and makes it essential to evaluate the asphalt performance to control its common failure such as moisture sensitivity. Although the amount of bitumen in asphalt mixtures is not high, it has a significant impact on mixture performance. So, when the performance of modified bitumen improved by additives, it would result in better performance of asphalt mixture. Evaluation of moisture sensitivity in modified asphalt mixture by adding Zycotherm and Evonic as bitumen modifiers has been studied in this research. Limestone graded number 4, bitumen with 60-70 penetration grade and two nanomaterial additives called Zycotherm and Evonic in two different percentage (0.1 and 0.3 weight percentage of bitumen) have been used to make the asphalt mixture samples in this study. In order to evaluate the effects of these two nanomaterials on moisture sensitivity of asphalt mixture, the indirect tensile strength test (modified Lotman test) and Texas boiling test has been performed. In addition, Marshal stability test, resilient modulus test and dynamic creep test have been done on both modified and unmodified asphalt mixture samples. A comparison between the test’s results of modified and unmodified mixtures shows a better sustainability of asphalt against moisture by using Zycotherm and Evonic as bitumen modifiers. The suitable portion of each nanomaterial additives are 0.1 percentage for Zycotherm and 0.3 percentage for Evonic. Moreover, the results show that the Zycotherm is more effective on improvement of moisture sensivity and performance of asphalt mixture.

Creep compliance is one of the fundamental tests of Mechanistic- Empirical flexible pavement design procedure in the AASHTO 2002 design guide. In this research, a new Artificial Neural Network model for estimating the HMA creep compliance with the generalization ability of R=0.949 has been developed successfully using feed forward multi layer perceptron Artificial Neural Networks (ANNs) with Levenberg-Marquardt back propagation training algorithm. The ANN model has 14 inputs including selected percent passings from aggregate gradation curve, asphalt content, asphalt penetration degrees at 77 and 125 Fahrenheit , asphalt penetration index and test temperature. The model has 8 outputs consist of creep compliances of Hot Mix Asphalt at 1, 2, 5, 10, 20, 50, 100 seconds and Poisson coefficient. All needed data has been extracted from LTPP database 2007 by developing many programs by SQL in Access 2000. As the result, 975 creep compliance tests data and 975 associated aggregate tests data series and 975 associated asphalt tests data series has been extracted successfully for ANNs training and evaluation.